Device and method for qualitative and quantitative analysis of heavy metals utilizing rotary disc system

ABSTRACT

The present invention relates to a device and a method for qualitative and quantitative analysis of heavy metals and more particularly provides a device and a method for qualitative and quantitative analysis of heavy metals utilizing a rotary disc system.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a national phase entry under 35 U.S.C. § 371 ofInternational Patent Application No. PCT/KR2018/012738, filed on Oct.25, 2018, published in Korean, which claims priority from Korean PatentApplication No. 10-2017-0154395, filed on Nov. 20, 2017, and KoreanPatent Application No. 10-2018-0053639, filed on May 10, 2018, thedisclosures of which are hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a device and a method for qualitativeanalysis and quantitative analysis of heavy metals and, moreparticularly, to a device and a method for qualitative analysis andquantitative analysis of heavy metals using a rotatable disk system.

Description of the Related Art

In general, the most widely used method for detecting heavy metals isspectroscopic analysis such as inductively coupled plasma massspectrometry or atomic absorption/emission spectrometry. Massspectrometry and spectroscopy based heavy metal detection methods areaccurate and have high detection limits, but they are expensive andrequire skilled analytical techniques, making it difficult to perform aheavy metal analysis in the field quickly and simply.

It is required to develop economical and cost-effective colordevelopment based heavy metal analysis system for replacing expensivemass spectrometry and spectroscopy based heavy metal analysis equipment,and development of miniaturized analysis system that can be convenientlyapplied in the field is required. In addition, it is required to developa system capable of qualitative analysis as well as qualitative analysisof heavy metals while shortening analysis time by performingsimultaneous detection of multiple heavy metals.

In addition, in the case where a plurality of heavy metals exist in onefluid sample, it is required to implement a method for performing theanalysis more easily and quickly

In addition, when a fluid sample containing heavy metals is developed ina detection unit and quantitative analysis is performed according to adevelopment distance, a method for performing a more accuratequantitative analysis is required. Further, there is a need for a methodfor performing the movement of the fluid sample more uniformly when thefluid sample is developed in the detection unit and preventing themoisture condensation phenomenon in the detection unit.

SUMMARY OF THE INVENTION

The present invention pertains to a device for qualitative analysis andquantitative analysis comprising a rotatable platform and a plurality ofmicrofluidic structures disposed radially and symmetrically on therotatable platform. Each of the plurality of the microfluidic structurescomprises a sample injection unit into which a fluid sample containingheavy metals is injected; a microfluidic channel (a siphon channel)which is a passage through which the sample can be moved to a detectionunit and connects the sample injection unit to the one end of thedetection unit; the detection unit comprising a plurality of detectionmembers, which is coated with an organic substance capable of causingthe color development reaction with the heavy metals of the sample; anda ruler for measuring the color developed distance. Each of theplurality of the microfluidic structures may receive different kinds ofsamples. The rotation of the device is controlled so that the samplemoves from the sample injection unit to the microfluidic channel andthen to the detection unit, and the qualitative analysis through thecolor development reaction of the heavy metals in the detection unit andthe quantitative analysis through the measurement of the color developeddistance may be possible.

Further, in the device for qualitative analysis and quantitativeanalysis according to the present invention, each of the plurality ofthe detection members may be coated with respective different reagents.

Further, in the device for qualitative analysis and quantitativeanalysis according to the present invention, each of the plurality ofthe detection members may comprise a plurality of sections coated withorganic ligands of respective different concentrations.

Further, in the device for qualitative analysis and quantitativeanalysis according to the present invention, the detection unit maycomprise a reservoir area which connects each one end of the pluralityof the detection members with the microfluidic channel.

Further, in the device for qualitative analysis and quantitativeanalysis according to the present invention, each of the detectionmembers comprises a plurality of sections coated with organic ligands ofrespective different concentrations, and the concentration of theorganic ligand coated in the section located i-th from the reservoirarea may be lower than the concentration of the organic ligand coated inthe section located i-1-th from the reservoir area, wherein i may be anatural number from 1 to n.

Further, the device for qualitative analysis and quantitative analysisaccording to the present invention further comprises an air circulationchannel connecting between the sample injection unit and the other endof the detection unit, wherein the air circulation channel can increasethe rate of evaporation of the fluid sample in the detection unit andprevent moisture condensation phenomenon in the detection unit.

Further, in the device for qualitative analysis and quantitativeanalysis according to the present invention, the sample injection unitmay include a space capable of receiving the sample and an openingthrough which the sample can be injected.

Further, in the device for qualitative analysis and quantitativeanalysis according to the present invention, the control of the rotationof the device can be accomplished by rotating the device firstly andthen stopping so that the sample injected into the sample injection unitis moved to the microfluidic channel; rotating the device secondarily sothat the sample moved to the microfluidic channel is moved to thereservoir area; and stopping the device so that the sample moved to thereservoir area is developed in the detection unit.

Further, in the device for qualitative analysis and quantitativeanalysis according to the present invention, the microfluidic channelmay include a portion of a “U” shaped tube so that the sample can bereceived within the microfluidic channel after the first rotation andbefore the second rotation of the device.

Also, in the device for qualitative analysis and quantitative analysisaccording to the present invention, the first rotation may be performedat 2000 to less than 4000 RPM for 5 to 2.0 seconds and the secondrotation may be performed at 4000 to 6000 RPM for 3 to 10 seconds.

Further, in the device for qualitative analysis and quantitativeanalysis according to the present invention, the rotatable platform is acircular disk and may have a diameter of 12 cm to 20 cm.

Further, in the device for qualitative analysis and quantitativeanalysis according to the, present invention, the heavy metals that maybe included in the sample may comprise Fe²⁺, Zn²⁺, Hg²⁺, Cr⁶⁺, Ni²⁺, orCu²⁺.

Further, in the device for qualitative analysis and quantitativeanalysis according to the present invention, the organic materialpreviously applied to the detection unit may comprise any one selectedfrom the group consisting of dimethylglyoxime, bathophenanthroline,dithiooxamide, dithizone, diphenylcarbazide and1-(2-pyridylazo)-2-naphthol.

Further, the present invention pertains to an analytic method of a fluidsample containing heavy metals by using the qualitative analysis andquantitative analysis device according to the present ion. The analyticmethod comprises: (S1) injecting the sample into the sample injectionunit; (S2) controlling the rotation of the device; and (S3) performingat least one of qualitative analysis and quantitative analysis of thesample developed in the detection unit.

Further, in the analytic method of a fluid sample containing heavymetals according to the present invention, the injection of the sampleinto the sample injection unit of the step (S1) may comprise injectingthe fluid sample containing different kinds of the heavy metals intoeach of the plurality of the microfluidic structures, or injecting thefluid sample containing same kinds of the heavy metals of varyingconcentrations into each of the plurality of the micro fluidicstructures.

Further, in the analytic method of a fluid sample containing heavymetals according to the present invention, the controlling of therotation of the device of the step (S2) may comprise (S2-1) rotating thedevice firstly and then stopping so that the sample injected into thesample injection unit is moved to the microfluidic channel; (S2-2)rotating the device secondarily so that the sample moved to themicrofluidic channel is moved to the reservoir area; and (S2-3) stoppingthe rotation of the device so that the sample moved to the reservoirarea is developed in the detection unit.

Further, in the analytic method of a fluid sample containing heavymetals according to the present invention, the performance of at leastone of qualitative analysis and quantitative analysis of the sample ofthe step (S3) may comprise performing at least one of (S3-1) qualitativeanalysis through the color development reaction of the sample developedin the detection unit and (S3-2) quantitative analysis through themeasurement of the color developed distance.

EFFECT OF THE INVENTION

According to the device for qualitative analysis and quantitativeanalysis and the analysis method of the sample using the same accordingto one embodiment of the present invention, the increase of thedetection limit of heavy metals through the control of the automatedfluidic control and the control of the torque and capillary force ispossible. It is possible to improve the detection limit of heavy metalions by the torque control. That is, it is possible to improve thedetection limit by controlling the color development reaction time andthe colored area via adjustment of the centrifugal force and thecapillary force by control of the rotation of the device.

According to the device for qualitative analysis and quantitativeanalysis and the analysis method of the sample using the same accordingto one embodiment of the present invention, qualitative analysis andquantitative analysis of several heavy metals can be performed with onedevice. According to the present invention, economical and rapidmulti-metal qualitative/quantitative analysis is possible. It is moreeconomical than conventional expensive spectroscopy or mass spectrometrybased heavy metal detector and can shorten analysis time. In addition,the configurations for qualitative analysis and quantitative analysiscan be integrated into one miniaturized device, and can be appliedquickly and conveniently in the field where qualitative/quantitativeanalysis of heavy metals is required.

In addition, since the channel (a microfluidic channel) and thedetection unit are all patterned in one device, the fabrication of thedevice for qualitative analysis and quantitative analysts is simple.

In addition, in the device for qualitative analysis and quantitativeanalysis according to the present invention, even when multiple heavymetals are present in one fluid sample, the analysis can be performedmore simply and quickly

In addition, it is possible to improve the accuracy of the measurementeven in the quantitative analysis of heavy metals contained in the fluidsample, by coating each of the detection members with organic ligandswith a concentration gradient in place of coating with the sameconcentration of the organic ligands throughout each of the detectionmembers.

Further, according to the device for qualitative analysis andquantitative analysis and the analysis method of the sample using thequalitative analysis and quantitative analysis device according to oneembodiment of the present invention, the air circulation channel isprovided so that the moisture condensation in the detection unit can beprevented when the fluid sample is developed in the detection unit andthe reservoir area is provided at the end of the microfluidic channel sothat one end of the detection unit is located in the reservoir area, andthus the fluid sample can move more uniformly when the fluid sample isdeveloped in the detection unit.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A shows a device for qualitative analysis and quantitativeanalysis according to one embodiment of the present invention, and FIGS.1B and 1C show microfluidic structures of the device for qualitativeanalysis and quantitative analysis of FIG. 1A.

FIG. 1D shows a device for qualitative analysis and quantitativeanalysis according to another embodiment of the present invention, andFIGS. 1E and 1F show microfluidic structures of the device forqualitative analysis and quantitative analysis of FIG. 1D.

FIG. 1G shows a device for qualitative analysis and quantitativeanalysis according to another embodiment of the present invention, andFIGS. 1H and 1I show microfluidic structures of the device forqualitative analysis and quantitative analysis of FIG. 1G.

FIG. 2A illustrates a device for qualitative analysis and quantitativeanalysis according to another embodiment of the present invention, andFIG. 2B shows microfluidic structures of the device for qualitativeanalysis and quantitative analysis of FIG. 2A.

FIGS. 3A to 3C show each layer of a rotatable platform comprisingmicrofluidic structures of the device for qualitative analysis andquantitative analysis according to FIGS. 1A, 1D and 1G, respectively.

FIGS. 4A to 4D show each layer of a rotatable platform comprisingmicrofluidic structures of the device for qualitative analysis andquantitative analysis according to FIG. 2A.

FIG. 5 shows an example of a color development reaction between heavymetal ions and organic complexing agents.

FIG. 6 shows an example of simultaneous qualitative analysis of heavymetals using the device for qualitative analysis and quantitativeanalysis according to the present invention.

FIGS. 7A and 7B show examples of quantitative analysis of heavy metalsusing the device for qualitative analysis and quantitative analysisaccording to the present invention.

FIG. 8 shows a flowchart of a method of analyzing a sample using thedevice for qualitative analysis and quantitative analysis according tothe present invention.

FIG. 9 shows a system for qualitative analysis and quantitative analysisthat includes and can rotate the device for qualitative analysis andquantitative analysis according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

In the device for qualitative analysis and quantitative analysiscomprising a rotatable platform and a plurality of microfluidicstructures disposed radially and symmetrically on the rotatable platformaccording to present invention, each of the plurality of themicrofluidic structures comprises a sample injection unit into which afluid sample containing heavy metals is injected; a microfluidic channelwhich is a passage through which the sample can be moved to a detectionunit and connects the sample injection unit to the one end of thedetection unit; the detection unit comprising a plurality of detectionmembers, which is coated with an organic substance capable of causingthe color development reaction with the heavy metals of the sample; anda ruler for measuring the color developed distance. Each of theplurality of the microfluidic structures may receive different kinds ofsamples. The rotation of the device is controlled so that the samplemoves from the sample injection unit to the microfluidic channel andthen to the detection unit, and the qualitative analysis through thecolor development reaction of the heavy metals in the detection unit andthe quantitative analysis through the measurement of the color developeddistance may be possible.

Further, in the device for qualitative analysis and quantitativeanalysis according to the present invention, each of the plurality ofdetection members may be coated with respective different reagents.

Further, in the device for qualitative analysis and quantitativeanalysis according to the present invention, each of the detectionmembers may comprise a plurality of sections coated with organic ligandsof respective different concentrations.

Further, in the device for qualitative analysis and quantitativeanalysis according to the present invention, the detection unit maycomprise a reservoir area which connects each one end of the pluralityof detection members with the microfluidic channel.

Further, in the device for qualitative analysis and quantitativeanalysis according to the present invention, the development areacomprises a plurality of sections coated with organic ligands ofrespective different concentrations, and the concentration of theorganic ligand coated in the section located i-th from the reservoirarea may be lower than the concentration of the organic ligand coated inthe section located i-1-th from the reservoir area, wherein i may be anatural number from 1 to n. Further, the device for qualitative analysisand quantitative analysis according to the present invention furthercomprises an air circulation channel connecting between the sampleinjection unit and the other end of the detection unit, wherein the aircirculation channel can increase the rate of evaporation of the fluidsample in the detection unit and prevent moisture condensationphenomenon in the detection unit.

Further, in the device for qualitative analysis and quantitativeanalysis according to the pr sen invention, the sample injection unitmay include a space capable of receiving the sample and an openingthrough which the sample can be injected.

Further, in the device for qualitative analysis and quantitativeanalysis according to the present invention, the control of the rotationof the device can be accomplished by rotating the device firstly andthen stopping so that the sample injected into the sample injection unitis moved to the microfluidic channel; rotating the device secondarily sothat the sample moved to the microfluidic channel is moved to thereservoir area; and stopping the device so that sample moved to thereservoir area is developed in the detection unit.

Further, in the device for qualitative analysis and quantitativeanalysis according to the present invention, the microfluidic channelmay include a portion of a “U” shaped tube so that the sample can bereceived within the microfluidic channel after the first rotation andbefore the second rotation of the device.

Also, in the device for qualitative analysis and quantitative analysisaccording to the present invention, the first rotation may be, performedat 2000 to 4000 RPM for 5 to 20 seconds and the second rotation may beperformed at 4000 to 6000 RPM for to 10 seconds.

Further, in the device for qualitative analysis and quantitativeanalysis according to the present invention, the rotatable platform is acircular disk and may have a diameter of 12 cm to 20 cm.

Further, in the device for qualitative analysis and quantitativeanalysis according to the present invention, the heavy metals that maybe included in the sample may comprise Fe²⁺, Zn²⁺, Cr⁶⁺, Ni ²⁺, or Cu²⁺.

Further, in the device for qualitative analysis and quantitativeanalysis according to the present invention, the organic materialpreviously applied to the detection unit may comprise any one selectedfrom the group consisting of dimethylglyoxime, bathophenanthroline,dithiooxamide, dithizone, diphenylcarbazide and1-(2-pyridylazo)-2-naphthol.

Further, in the analytic method of a fluid sample containing heavymetals by using the qualitative analysis and quantitative analysisdevice according to the present invention, the method comprises: (S1)injecting the sample into the sample injection unit; (S2) controllingthe rotation of the device; and (S3) performing at least one ofqualitative analysis and quantitative analysis of the sample developedin the detection unit.

Further, in the analytic method of a fluid sample containing heavymetals according to the present invention, the injection of the sampleinto the sample injection unit of the step (S1) may comprise injectingthe fluid sample containing different kinds of the heavy metals intoeach of the plurality of the microfluidic structures, or injecting thefluid sample containing same kinds of the heavy metals of varyingconcentrations into each of the plurality of the microfluidicstructures.

Further, in the analytic method of a fluid sample containing heavymetals according to the present invention, the controlling of therotation of the device of the step (S2) may comprise (S2-1) rotating thedevice firstly and then stopping so that the sample injected into thesample injection unit is moved to the microfluidic channel; (S2-2)rotating the device secondarily so that the sample moved to themicrofluidic channel is moved to the reservoir area; and (S2-3) stoppingthe rotation of the device so that the sample moved to the reservoirarea is developed in the detection unit. Further, in the analytic methodof a fluid sample containing heavy metals according to the presentinvention, the performance of at least one of qualitative analysis andquantitative analysis of the sample of the step (S3) may compriseperforming at least one of (S3-1) qualitative analysis through the colordevelopment reaction of the sample developed in the detection unit and(S3-2) quantitative analysis through the measurement of the colordeveloped distance.

Hereinafter, the device and the method for qualitative analysis andquantitative analysis of heavy metals using a rotatable disk systemaccording to the present invention will be described in detail. Theaccompanying drawings, which are included to provide a furtherunderstanding of the invention, illustrate embodiments of the presentinvention and the technical scope of the present invention is notlimited thereto.

In addition, the same or corresponding components are denoted by thesame reference numbers regardless of the figures, and redundantdescription thereof krill be omitted. For convenience of explanation,the size and shape of each constituent member shown may be exaggeratedor reduced.

FIG. 1A shows a device for qualitative analysis and quantitativeanalysis (1) according to one embodiment of the present invention, andFIG. 1B shows microfluidic structures (20) of the rotatable disk systemof FIG. 1A.

First, referring FIG. 1A, the device for qualitative analysis andquantitative analysis (1) includes the rotatable platform (10) and aplurality of the microfluidic structures (20) provided on the rotatableplatform (10). The rotatable platform (10) may be, for example, acircular disk, and the size may be, for example, in one embodiment 12 cmto 20 cm in diameter, and in another embodiment, less than 12 cm indiameter.

The rotatable platform (10) includes the plurality of the microfluidicstructures (20) which positioned radially and symmetrically on therotatable platform (10). For example, the plurality of the microfluidicstructures (20) may comprise two, three, four, six, eight, ten, ortwelve of the structures. In FIG. 1A, three microfluidic structures (20)are shown disposed on the rotatable platform (10).

Referring to FIG. 1B, each microfluidic structure (20) of the pluralityof the microfluidic structures (20) is shown. The microfluidicstructures (20) include a top layer (see FIG. 3A), a detection unit(120) coated with an organic substance capable of causing a colordevelopment reaction with the heavy metals in a fluid sample, and abottom layer (see FIG. 3A). The top layer includes a sample injectionunit (100) into which a fluid sample containing the heavy metals isinjected, a microfluidic channel (110) through which the fluid samplecan move to the detection unit, a portion where the detection unit (120)can be inserted, and a ruler (130) for measuring the color developeddistance. The bottom layer is a pressure-sensitive adhesive layer whichis not patterned.

Each microfluidic structure (20) of the plurality of the microfluidicstructures (20) may receive the fluid sample containing different kindsof the heavy metals. The heavy metals that may be included in the fluidsample may include, for example, Fe²⁺, Zn²⁺, Hg²⁺, Cr⁶⁺, Ni²⁺, Cu²⁺,etc.

The sample injection unit (100) includes a space for accommodating afluid sample containing the heavy metals and an opening (100 a) throughwhich the fluid sample can be injected into the space. The sampleinjection unit (100) and one end of the detection unit (120) may beconnected to the microfluidic channel (110). Further, the sampleinjection unit (100) may include a blocking unit (100 b) which preventsthe sample injected through the opening (100 a) from flowing directlyinto the microfluidic channel (110) and stores the sample in the innerspace of the sample injection unit (100) by using drop of the channel.Since the vicinity of the rear end portion (100 c) of the sampleinjection unit (100) where the microfluidic channel (110) is connectedto the sample injection unit (100) has, for example, a streamlinedshape, when the fluid sample injected into the injection unit (100)moves to the microfluidic channel (110), the resistance of the fluidsample is minimized and all of the fluid sample injected into the sampleinjection unit (100) is moved to the microfluidic channel (110).

The microfluidic channel (110) may have a width of 1 min and a depth of100 μm. The microfluidic channel (110) may comprise, for example, aportion of a “U” shaped tube. As will be described below, the fluidsample including the heavy metals after the first rotation and beforethe second rotation of the device for qualitative analysis andquantitative analysis (1) can move along the channel which is a passagethrough which the fluid sample moves due to the hydrophilicity of themicrofluidic channel (110), and as a result, the fluid sample can beaccommodated in the microfluidic channel (110).

The detection unit (120) may be made of a porous hydrophilic material,for example, paper, nitrocellulose, cotton, silica based sol-gel matrix,etc., and may be preferably made of paper.

Meanwhile, the detection unit (120) comprises a plurality of thedetection members (121, 122, 123). Although FIGS. 1A and 1B show onedetection unit (120) comprising three detection members (121, 122, 123),the present invention is not limited thereto and the number of thedetection members may be adjusted according to various environments inwhich the present invention is implemented. Each of the plurality of thedetection members (121, 122, 123) of the detection unit (120) may becoated with different reagents. These pre-applied reagents each containa specific organic material (organic ligand) that can cause a colordevelopment reaction with the heavy metals in the fluid sample (see FIG.5 and Table 1). Therefore, when one organic sample injected into thesample injection unit (100) includes a plurality of the heavy metals,the plurality of the heavy metals may be detected in each of theplurality of the detection members (121, 122, 123) coated with each ofthe different reagents. For example, PAN (1-(2-pyridylazo)-2-naphthol)for detecting Zn²⁺ may be coated in the detection member (121), Bphen(bathophenanthroline) for detecting Fe²⁺ may be coated in the detectionmember (122), and DMG (dimethylglyoxime) for detecting Ni²⁺ may becoated in the detection member (123).

Also, the detection unit (120) comprises a reservoir area (124)connecting the microfluidic channel (110) to the plurality of thedetection members (121, 122, 123). The reservoir area (124) may or maynot be coated with an organic material. The reservoir area (124) isconnected to each one end of the plurality of the detection members(121, 122, 123). Further, the microfluidic channel (110) is connected tothe reservoir area (124). The fluid sample moved from the sampleinjection unit (100) to the microfluidic channel (110) during the firstrotation of the rotatable platform (10) is moved from the microfluidicchannel (110) to the reservoir area (124) of the detection unit (120)connected to the microfluidic channel (110) during the secondaryrotation of the rotatable platform (10). At this time, the fluid sampleremains in the reservoir area (124) without being developed into theplurality of the detection members (121, 122, 123) of the detection unit(120) by the centrifugal force due to the rotation. When the secondaryrotation of the rotatable platform (10) is stopped, the fluid sample isdeveloped from the reservoir area (124) to each of the plurality of thedetection members (121, 122, 123). A more detailed description thereofwill be given below with reference to FIG. 8 .

The ruler (130) is positioned alongside of the detection unit (120) inthe vicinity of the detection unit (120). The ruler (130) may be, forexample, scaled in millimeters (mm). Alternatively, it may be scaled inunits of concentration such as ppm, ppb, etc., in addition to the lengthunit such as mm in the scale unit (130). In the case where the scale isexpressed in terms of the concentration unit in the ruler (130), it maybe expressed in terms of a concentration unit obtained by substitutingthe development distance of the relevant heavy metals into a calibrationcurve (see FIGS. 6A and 6B).

FIG. 1C shows exemplary dimensions of the microfluidic structures (20)of the rotatable disk system of FIG. 1B. Exemplary dimensions of themicrofluidic structures (20) are not limited to those shown in FIG. 1C,but may be modified or changed according to various environmentsembodied in the present invention.

FIG. 1D shows a device for qualitative analysis and quantitativeanalysis (1′) according to another embodiment of the present invention,and FIG. 1E shows the microfluidic structures (20′) of the rotatabledisk system of FIG. 1D.

Each of the plurality of the detection members (121′, 122′, 123′) of thedetection unit (120′) is not coated with the organic ligands of the sameconcentration but coated with organic ligands of differentconcentrations by providing a concentration gradient in a plurality of(n, where n is a natural number of 2 or more) sections of the detectionmembers (121′, 122′, 123′) as shown in FIG. 1E. The number n of sectionsmay be, for example, 2 or more and 10 or less, or 5 or 6, for example.More specifically, upon checking the detection member (121′), the firstsection (121′₁) closest to the reservoir area (124) is coated with thehighest concentration of the organic ligand, and the next adjacentsecond section (121′₂) is coated with a lower concentration than that ofthe organic ligand coated in the first section (121′₁). The next thirdsection (121′₃) is coated with a lower concentration than that of theorganic ligand coated in the second section (121′₂), and the subsequentsections are also coated with increasingly lower concentrations of theorganic ligands. And the n-th section (121′_(n)) farthest from thereservoir area (124) is coated with the lowest concentration of theorganic ligand. That is, the concentration of the organic ligand coatedin the i-th section (121′_(i)) from the reservoir area (124) is lowerthan that of the organic ligand coated in the (i-1)-th section(121′_(i-1)). Here, i is a natural number from 1 to n.

The amount of the fluid sample developed from the n-th section(121′_(n)) farthest to the reservoir area (124) toward the first section(121′₁) closest to the reservoir area (124) increases. According to thepresent invention, the concentration of the coated organic ligand isincreased toward the first section (121′₁) closest to the reservoir area(124) from the n-th section (121′_(n))farthest from the reservoir area(124). It is possible to prevent the speed at which the fluid sample isdeveloped at the detection member (121′) from being increased fasterthan the rate at which the organic ligand coated on the detection member(121′) reacts with the heavy metals in the fluid sample (colordevelopment reaction) so that in the analysis of the heavy metals in thefluid sample, the accuracy of the measurement can be further increased.On the other hand, the detection member (122′) and the detection member(123′) are also coated with organic ligands with the concentrationgradient in the above-described manner with respect to the detectionmember (121′).

For example, when in order to detect Zn²⁺, PAN(1-(2-pyridylazo)-2-naphthol) as an organic substance is coated on oneof the detection members (121′, 122′, 123′) (for example, the detectionmember (121′)). When the number of sections of the detection member is5, the concentration of the organic ligand coated on each of the firstsection (121′₁), the second section (121′₂), the third section (121′₃),the fourth section (121′₄) and the fifth section (121′₅) is 50, 35, 20,5 and 1 mM, respectively.

Also, for example, when in order to detect Fe²⁺, Bphen(bathophenanthroline) as an organic substance is coated on one of thedetection members (121′, 122′, 123′) (for example, the detection member(121′)). When the number of sections of the detection member is 5, theconcentration of the organic ligand coated on each of the first section(121′₁), the second section (121′₂), the third section (121′₃), thefourth section (121′₄) and the fifth section (121′₅) is 10, 5, 1, 0.5and 0.1 mM, respectively.

Further, for example, when in order to detect Ni²⁺, DMG(dimethylglyoxime) as an organic substance is coated on one of thedetection members (121′, 122′, 123′) (for example, the detection member(121′)). When the number of sections of the detection member is 5, theconcentration of the organic ligand coated on each of the first section(121′₁), the second section (121′₂), the third section (121′₃), thefourth section (121′₄) and the fifth section (121′₅) is 50, 10, 5, 1 and0.5 mM, respectively.

Also, for example, when in order to detect Cu²⁺, DTO (dithiooxamide) asan organic substance is coated on one of the detection members (121′,122′, 123′) (for example, the detection member (121′)). When the numberof sections of the detection member is 5, the concentration of theorganic ligand coated on each of the first section (121′₁), the secondsection (121′₂), the third section (121′₃), the fourth section (121′₄)and the fifth section (121′₅) is 10, 8, 6, 4 and 2 mM, respectively.

Further, for example, when in order to detect Cr⁶⁺, DCB(diphenylcarbazide) supplemented with 1% H₂SO₄ as an organic substanceis coated on one of the detection members (121′, 122′, 123′) (forexample, the detection member (121′)). When the number of sections ofthe detection member is 5, the concentration of the organic ligandcoated on each of the first section (121′₁), the second section (121′₂),the third section (121′₃), the fourth section (121′₄) and the fifthsection (121′₅) is 20, 10, 5, 2 and 1 mM, respectively.

Also, for example, when in order to detect Hg²⁺, DTZ (dithizone) as anorganic substance is coated on one of the detection members (121′, 122′,123′) (for example, the detection member (121′)). When the number ofsections of the detection member is 5, the concentration of the organicligand coated on each of the first section (121′₁), the second section(121′₂), the third section (121′₃), the fourth section (121′₄) and thefifth section (121′₅) is 50, 25, 10, 5 and 1 mM, respectively.

FIG. 1F shows exemplary dimensions of the microfluidic structures (20′)of the rotatable disk system of FIG. 1D. Exemplary dimensions of themicrofluidic structures (20′) are not limited to those shown in FIG. 1F,but may be modified or changed according to various environmentsembodied in the present invention.

FIG. 1G shows a device for qualitative analysis and quantitativeanalysis (1″) according to another embodiment of the present invention,and FIG. 1H shows the microfluidic structures (20″) of the rotatabledisk system of FIG. 1G. The device for qualitative analysis andquantitative analysis (1″) of FIG. 1H, like the device for qualitativeanalysis and quantitative analysis (1) of FIG. 1A, comprises therotatable platform (10) and a plurality of the microfluidic structures(20″) provided in and the rotatable platform (10). The top layer of therotatable platform (10) includes the sample injection unit (100) intowhich a fluid sample containing the heavy metals is injected and themicro-fluidic channel (110) which is a passage through which the fluidsample can move to the detection unit. The portion of the top layerwhere the detection unit (120″) is positioned may be variously modifiedand changed so that the detection unit (120″) can be inserted, includinga concave portion in conformity with the shape of the detection unit(120″). Also, the depth of the concave portion can be variously modifiedand changed according to the environment in which the present inventionis actually implemented. The bottom layer includes a portion where thedetection unit (120″) can be inserted (see FIG. 3C) and a ruler (130)for measuring the color developed distance.

Meanwhile, the device for qualitative analysis and quantitative analysis(1″) of FIG. 1G comprises an air circulation channel (140) unlike thedevice for qualitative analysis and quantitative analysis (1, 1′) ofFIGS. 1A and 1D. The air circulation channel (140) connects between thesample injection unit (100) and the other end of each of the pluralityof the detection members (121′, 122′, 123′) of the detection unit(120′). Due to this, the sample injection unit (100), the microfluidicchannel (110), the detection unit (120′), the air circulation channel(140), and the sample injection unit (100) are connected to becirculated in order. By introducing the air circulation channel (140),the evaporation rate of the fluid sample of the detection unit (120′)may be increased, and the moisture condensation phenomenon in thedetection unit (120′) may be prevented. On the other hand, with respectto the sample injection unit (100), since the air circulation channel(140) is located at the center of the circular disk-shaped rotatableplatform (10) and the microfluidic channel (110) is positioned towardthe edge of the rotatable platform (10), when the rotatable platform(10) rotates, the sample of the sample injection unit (100) moves to themicrofluidic channel (110) by the centrifugal force and does not move tothe air circulation channel (140). Additionally, in order to prevent thepossibility of movement, a hole having a depth of about 1 mm and adiameter of about 0.8 mm is drilled at a point where the sampleinjection unit (100) and the air circulation channel (140) are connectedto each other to form a capillary valve operated by an air pressure,thereby preventing the sample from moving from the sample injection unit(100) to the air circulating channel (140).

FIG. 1I shows exemplary dimensions of the microfluidic structures (20″)of the rotatable disk system of FIG. 1G. Exemplary dimensions of themicrofluidic structures (20″) are not limited to those shown in FIG. 1I,but may be modified or changed according to various environmentsembodied in the present invention.

FIG. 2A illustrates a device for qualitative analysis and quantitativeanalysis (1′″according to another embodiment of the present invention,and FIG. 2B shows the microfluidic structures (20′″) of the rotatabledisk system of FIG. 2A. The device for qualitative analysis andquantitative analysis (1′″) of FIG. 2A comprises, like the device forqualitative analysis and quantitative analysis (1) of FIG. 1A, therotatable platform (10) and a plurality of the microfluidic structures(20′″) provided in and the rotatable platform (10). The top layer of therotatable platform (10) includes the sample injection unit (100) intowhich a fluid sample containing the heavy metals is injected and themicrofluidic channel (110) which is a passage through which the fluidsample can move to the detection unit. The portion of the top layerwhere the detection unit (120′″) is positioned may be variously modifiedand changed so that the detection unit (120′″) can be inserted,including a concave portion in conformity with the shape of thedetection unit (120′″). Also, the depth of the concave portion can bevariously modified and changed according to the environment in which thepresent invention is actually implemented. The bottom layer includes aportion where the detection unit (120′″) can be inserted (see FIG. 4D)and a ruler (130) for measuring the color developed distance.

The device for qualitative analysis and quantitative analysis (1′″) ofFIG. 2A comprises an air circulation channel (140′) like the device forqualitative analysis and quantitative analysis (1″) of FIG. 1G. The aircirculation channel (140′) connects between the sample injection unit(100) and the other end of the detection unit (120″). Due to this, thesample injection unit (100), the microfluidic channel (110), thedetection unit (120″), the air circulation channel (140′), and thesample injection unit (100) are connected to be circulated in order.

Meanwhile, in the device for qualitative analysis and quantitativeanalysis (1′″) of FIG. 2A, the detection unit (120″) comprises onedetection member. Further, the detection unit (120″) does not havedifferent concentrations of the organic ligands in each section unlikein the device for qualitative analysis and quantitative analysis (1, 1′)of FIGS. 1D and 1G. Further, in the device for qualitative analysis andquantitative analysis (1′″) of FIG. 2A, the entire detection unit (120″)is coated with an organic material capable of causing the colordevelopment reaction with the heavy metals of the fluid sample so thatthe fluid sample can be developed and includes a reserve region (150)provided separately from the detection unit (120″). One end of thedetection unit (120″) is accommodated in the reservoir region (150). Thereservoir region (150) is a recessed patterned area in each of the lowersurface of the top layer and the upper surface of the bottom layer ofthe rotatable platform (10) of FIG. 4A so as to accommodate the fluidsample therein. The fluid sample accommodated in the microfluidicchannel (110) during the first rotation of the rotatable platform (10)moves from the microfluidic channel (110) to the reservoir region (150)during the second rotation of the rotatable platform (10) and then isstored (i.e., trapped) in the reservoir area (150) without beingdeveloped into the detection unit (120″) by the centrifugal force due tothe rotation. When the second rotation of the rotatable platform (10) isstopped, the fluid sample is moved from the reservoir area (150) intothe detection unit (120″) where the fluid sample is developed. A moredetailed description thereof will be given below with reference to FIG.8 .

In the description of the device for qualitative analysis andquantitative analysis (1′″) of FIG. 2A and the microfluidic structures(20′″) of FIG. 2B, the description of the components that overlap withthose in the device for qualitative analysis and quantitative analysis(1, 1′, 1″) and the microfluidic structures (20, 20′, 20″) of FIGS. 1Ato 1H refers to the descriptions of FIGS. 1A to 1H.

FIGS. 3A and 3B illustrate each layer of the rotatable platform (10)comprising the microfluidic structures (20, 20′) of FIGS. 1A and 1D,respectively. The rotatable platform (10) including the microfluidicstructures (20, 20′) is mainly composed of two layers. In a top layer,the sample injection unit (100), the microfluidic channel (110), a spacein which the detection unit (120, 120′) can be inserted, and the ruler(130) are positioned. The thickness of the top layer may be, forexample, 1.0 mm, and the materials of the top layer may include, forexample, polycarbonate (PC), polymethyl methacrylate (PMMA) and thelike. The sample injection unit (100) and the microfluidic channel (110)are provided within the top layer, and the sample inject unit (100) andthe microfluidic channel (110) can be formed through a patterningprocess using micro-milling. The portion of the top layer where thedetection unit (120, 120′) is positioned may be variously modified andchanged so that the detection unit (120, 120′) can be inserted,including a concave portion in conformity with the shape of thedetection unit (120, 120′). Also, the depth of the concave portion canbe variously modified and changed according to the environment in whichthe present invention actually implemented. The bottom layer is notpatterned but is a pressure sensitive adhesion layer that can be bondedto the top layer. The material thereof may include, for example, apolyolefin series and the like.

FIG. 3C illustrates each layer of the rotatable platform (10) comprisingthe microfluidic structures (20″) of FIG. 1G. As shown in FIG. 3C, therotatable platform (10) including the microfluidic structures (20″) ismainly composed of three layers, each of which corresponds to the toplayer wherein the sample injection unit (100) and the microfluidicchannel (110) are positioned, a bottom layer (see FIG. 4D) for insertingthe detection unit, and a PSA (Pressure sensitive adhesion) layer forbonding the top and bottom layers. The materials of the top and bottomlayers may include, for example, polycarbonate (PC), polymethylmethacrylate (PMMA) and the like. The sample injection unit (100) andthe microfluidic channel (110) are provided within the top layer, andthe sample injection unit (100) and the microfluidic channel (110) canbe formed through a patterning process using micro-milling. The portionof the top layer where the detection unit (120′) is positioned may bevariously modified and changed so that the detection unit (120′) can beinserted, including a concave portion in conformity with the shape ofthe detection unit (120′). Also, the depth of the concave portion can bevariously modified and changed according to the environment in which thepresent invention is actually implemented. A hydrophilic material iscoated on the inside of the microfluidic channel (110) to receive thefluid sample containing the heavy metals. To have a space in which thedetection unit (120′) can be inserted in the bottom layer, the lowersurface of the top layer may include a concave portion in conformitywith the shape of the detection unit (120′). The ruler (130) ispatterned in the bottom layer. The PSA layer is an adhesive layerserving to bond the top layer and the bottom layer, and can be formedinto, for example, an acryl based double-sided adhesive tape in a tapeor a plate having an adhesive component corresponding to the size of therotatable platform (10), the region corresponding to the sampleinjection unit (100) and the microfluidic channel (110) in the toplayer, and the region corresponding to the detection unit (120′) in thebottom layer may be removed by cutting or the like. On the other hand,the top layer and the PSA layer are made of a transparent material so hathe development of the sample in the detection unit (120″) and the rulerin the bottom layer can be identified. However, the present invention isnot limited to the above-described embodiments, and variousmodifications and changes are possible, for example, the ruler (130) maybe patterned on the top layer.

FIGS. 4A to 4D illustrate each layer of the rotatable platform (10)comprising the microfluidic structures (20′″) of FIG. 2A. As shown inFIG. 4A, the rotatable platform (10) including the microfluidicstructures (20″) is mainly composed of three layers, each of whichcorresponds to the top layer wherein the sample injection unit (100) andthe microfluidic channel (110) are positioned (see FIG. 4B), a bottomlayer (see FIG. 4D) for inserting the detection unit, and a PSA(Pressure sensitive adhesion) layer (see FIG. 4C) for bonding the topand bottom layers. In FIGS. 4A to 4D, the description of the device forqualitative analysis and quantitative analysis (1′″) of FIG. 2A and themicrofluidic structures (20′″) of FIG. 2B, and the respective layer thatoverlap with those in the device for qualitative analysis andquantitative analysis (1″) of FIG. 1G and the microfluidic structures(20″), and the respective layer refers to the descriptions of FIG. 3C.

According to the device for qualitative analysis and quantitativeanalysis (1, 1′, 1″, 1′″) of the present invention, the rotation of thedevice for qualitative analysis and quantitative analysis (1) iscontrolled so that the fluid sample containing the heavy metals movesfrom the sample injecting unit (100) into the microfluidic channel(110), and then moves to the detection unit (120, 120′, 120″). Forexample, after the fluid sample containing the heavy metals is injectedinto the sample injection unit (100), when the device for qualitativeanalysis and quantitative analysis (1, 1′, 1″, 1′″) is first rotated for10 seconds at 3000 RPM and then stopped, the fluid sample containing theheavy metals moves to the microfluidic channel (110). When the devicefor qualitative analysis and quantitative analysis (1, 1′, 1″, 1′″) issecondarily rotated at 5,000 RPM for 5 seconds, the fluid samplecontaining the heavy metals in the microfluidic channel (110) of the toplayer is injected to the detection unit (120, 120′, 120″) inserted inthe bottom layer by the centrifugal force. When the rotation of thedevice for qualitative analysis and quantitative analysis (1, 1′, 1″,1′″) is stopped, the fluid sample containing the heavy metals isdeveloped on the detection units (120, 120′, 120″) by the capillaryforce.

The fluid sample including the heavy metals developed on the detectionunit (120, 120′, 120″) reacts with the reagents previously coated on thedetection unit (120, 120′, 120″) to indicate colors related to the heavymetals. As an organic substance that can be previously applied to thedetection unit (120, 120′, 120″), for example, an organic chelatingagent may be used. In one embodiment, organic substances based on areaction list between heavy metal ions and the organic chelating agentsas shown in Table 1 below may be used.

TABLE 1 Heavy Metals Form Chelating agent (concentration) Nickel (Ni²⁺)Sulfate Dimethylglyoxime (100 mM) Iron (Fe²⁺) SulfateBathophenanthroline (5 mM) Copper (Cu²⁺) Sulfate Dithiooxamide (20 mM)Mercury (Hg²⁺) Sulfate Dithizone (5 mM) Chromium (Cr⁶⁺) OxideDiphenylcarbazide (10 mM) Zinc (Zn²⁺) Sulfate1-(2-Pyridylazo)-2-naphthol (5 mM)

FIG. 5 shows the color development reaction between heavy metal ions andthe organic chelating agents according to Table 1. In the embodiment ofFIG. 5 , PAN (1-(2-pyridylazo)-2-naphthol), Bphen (bathophenanthroline),DMG (dimethylglyoxime), DTO (dithiooxamide), DCB (diphenylcarbazide) andDTZ (dithizone) were used as the organic chelating agents. And 1% H₂SO₄was added to DCB for Cr⁶⁺ to improve the reaction selectivity of Cr⁶⁺ion for DCB and the color development reaction.

The device for qualitative analysis and quantitative analysis (1, 1′)according to the present invention can provide a simultaneousqualitative analysis up to a level of 25 ppm for a plurality of theheavy metals such as Fe²⁺, Zn²⁺, Hg²⁺, Ni²⁺, or Cu²⁺ within 15 minutes.

The qualitative analysis can be performed on the heavy metals containedin the fluid sample with the hue according to the color developmentreaction on the detection unit (120, 120′, 120″). For example, when thehue according to the color development reaction is observed with thenaked eyes, the types of the heavy metals contained in the fluid samplecan be identified. FIG. 6 shows an example of a simultaneous qualitativeanalysis for six heavy metals (100 ppm) using the device for qualitativeanalysis and quantitative analysis (1′″) of FIG. 2A.

In addition, the degree of development of the fluid sample including theheavy metals on the detection unit (120, 120′, 120″) can bequantitatively analyzed by using the ruler (130). Referring to theexample of FIG. 6 , it can be seen that the degree of development of thefluid sample including the heavy metals on the detection unit (120″) ofeach of the plurality of the microfluidic structures (20′″) is differentfrom each other. It is possible to measure the extent to which a fluidsample containing the heavy metals is developed by using the respectiveruler (130). The development distance of the corresponding fluid sampleon the detection unit (120) is measured using the ruler (130), the typesof heavy metals contained in the fluid sample are determined by theabove qualitative analysis, and the quantitative analysis of the heavymetals can be performed by substituting the development distance into acalibration curve for the heavy metals (see FIGS. 7A and 7B). As anexample of the quantitative analysis, FIG. 7A shows a case where Cr⁶⁺ isquantitatively analyzed and FIG. 7B shows a case where Fe²⁺ isquantitatively analyzed using the device for qualitative analysis andquantitative analysis (1′″) of FIG. 2A. For example, the numbers of 1ppm, 5 ppm, 10 ppm, 25 ppm, 50 ppm, and 100 ppm described in FIG. 7A arethe results of quantitative analysis of Cr⁶⁺. This is a method in whichthe degree of purple development corresponding to Cr⁶⁺ on the sixdetection units (120″) is measured using the ruler (130) and then themeasured development distance is substituted into the calibration curveof Cr⁶⁺ to obtain the concentration on the x axis corresponding to thedegree of development on the y axis of the calibration curve so as thatthe quantitative analysis of Cr⁶⁺ can be performed. In the case of Fe²⁺in FIG. 7B, the quantitative analysis can be performed the same manner.At this time, in the case of Cr⁶⁺, the detection limit of thequalitative analysis is 1 ppm and the detection limit of thequantitative analysis is 5 ppm. In the case of Fe²⁺, the detection limitof the qualitative analysis is 25 ppm and the detection limit of thequantitative analysis is 50 ppm.

Hereinafter, with reference to FIG. 8 , a method (2) of analyzing afluid sample containing the heavy metals using the device forqualitative analysis and quantitative analysis (1, 1′, 1″, 1′″)according to one embodiment of the present invention will be described.The steps of the method for analyzing a sample (2) according to anembodiment of the present invention are as follows:

Step 1: Injecting a fluid sample into the sample injection unit (100) ofthe device for qualitative analysis and quantitative analysis (1, 1′,1″, 1′″) (S1);

Step 2: Controlling the rotation of the device for qualitative analysisand quantitative analysis (1, 1′, 1″, 1′″) (S2); and

Step 3: Performing at least one of qualitative analysis and quantitativeanalysis (S3).

Step 1: Injecting a Fluid Sample into the Sample Injection Unit (100) ofthe Device for Qualitative Analysis and Quantitative Analysis (1, 1′,1″, 1′″) (S1)

The fluid sample is injected into each sample injection unit (100) ofthe plurality of the microfluidic structures (20) of the device forqualitative analysis and quantitative analysis (1, 1′, 1″, 1′″). Forexample, about 40 μl of the fluid sample each can be injected into eachsample injection unit (100). However, the present invention is notlimited to this embodiment, and the amount of the injection can bevariously adjusted according to various environments in which thepresent invention is implemented. The fluid sample containing differentkinds of the heavy metals are respectively injected into each of theplurality of the microfluidic structures (20, 20′, 20″, 20′″) (S1-1) toperform qualitative analysis and/or quantitative analysis as describedbelow, and the fluid sample containing the same kind of the heavy metalsof varying concentrations are respectively injected into each of themicrofluidic structures (20, 20′, 20″, 20′″) (S1-2) to performqualitative analysis and/or quantitative analysis as described below.

Step 2: Controlling the Rotation of the Device for Qualitative Analysisand Quantitative Analysis (1, 1′) (S2)

The device for qualitative analysis and quantitative analysis (1, 1′,1″, 1′″) is mounted on a system for qualitative analysis andquantitative analysis (3) capable of rotating the device for qualitativeanalysis and quantitative analysis (1, 1′, 1″, 1′″), for example, arotatable system for qualitative analysis and quantitative analysis (3)as shown in FIG. 9 , and the device for qualitative analysis andquantitative analysis (1, 1′, 1″, 1′″) is rotated. This step (S2)includes the following detailed steps:

Step 2-1: The device for qualitative analysis and quantitative analysis(1, 1′, 1″, 1′″) is initially rotated at 2000 to 4000 RPM for 5 to 20seconds and then is stopped to move the fluid sample including the heavymetals injected into the sample injection unit (100) located at the toplayer of the microfluidic structure (20, 20′, 20″, 20′″) to themicrofluidic channel (110) (S2-1).

Step 2-2: The device for qualitative analysis and quantitative analysis(1, 1′, 1″, 1′″) is secondarily rotated at 4000 to 6000 RPM for 3 to 10seconds to flow the fluid sample including the heavy metals transferredto the microfluidic channel (110) at step 2-1 into the reservoir region(124, 150) of the microfluidic structures (20, 20′, 20″, 20′″) (S2-2).

Step 2-3: The rotation of the device for qualitative analysis andquantitative analysis (1, 1′, 1″, 1′″) is stopped so that the fluidsample including the heavy metals are guided by the capillary force tobe developed on the detection unit (120, 120′, 120″) (S2-3).

Step 3: Performing at Least One of Qualitative Analysis and QuantitativeAnalysis (S3)

A qualitative analysis can be performed on the fluid sample developed onthe detection unit (120, 120′, 120″) by a method of analyzing the colordevelopment reaction on the detection unit (120, 120′, 120″) with thenaked eyes (S3-1), or a quantitative analysis can be performed bymeasuring the degree of development of the fluid sample developed on thedetection unit (120, 120′, 120″) by using a ruler (130) and thensubstituting the measured values to the calibration curves of thecorresponding heavy metals developed on the scale (S3-2), or both of thequalitative analysis and the quantitative analysis can be performed(S3-1 and S3-2). Examples related to this are described above withreference to FIGS. 6, 7A and 7B.

In summary, the device for qualitative analysis and quantitativeanalysis (1, 1′, 1″, 1′″) according to an embodiment of the presentinvention includes the microfluidic structures (20) having the samestructure that can detect a plurality of types (for example, six kinds)of the heavy metals on the rotatable platform (10) (for example, acircular disk), wherein each microfluidic structure (20) is arrangedradially and symmetrically along the rotational direction of therotatable platform (10) and comprises the detection unit (120, 120′,120″) coated with an organic substance that can cause a colordevelopment reaction with the heavy metals.

According to the device for qualitative analysis and quantitativeanalysis (1, 1′, 1″, 1′″) and the method of analyzing the sample usingthe same (2) according to the embodiment of the present invention, thecentrifugal force generated upon rotation of the device for qualitativeanalysis and quantitative analysis (1, 1′, 1″, 1′″) can move the fluidsample containing the heavy metals to the detection unit (120, 120′,120″) and the qualitative analysis can be performed through the colordevelopment reaction. Further, the fluid can be developed by the papercapillary force when the rotation of the device stops and thequantification may be performed by identifying the color developeddistance with the ruler (130) patterned on the device for qualitativeanalysis and quantitative analysis (1, 1′, 1″, 1′″). It is possible toincrease the detection limit of the heavy metals through automatic fluidcontrol and control of torque and capillary force. It is possible toimprove the detection limit of the heavy metal ions by the torquecontrol. That is, by adjusting the centrifugal force and the capillaryforce by the rotation control, it is possible to improve the detectionlimit by controlling the reaction time of color development and thecolored area. Specifically, on the detection unit, when the developmentspeed of the sample containing the heavy metals due to the capillaryforce becomes faster than the speed at which the heavy metals and theorganic chelating agent react with each other, the sample containing theheavy metals fails to sufficiently react with the organic chelatingagent and develops on the entire detection unit. In the case of a heavymetal sample having a high concentration, there is no problem indetection because of the color development, but there is a possibilitythat the quantitative property is lowered. In the case of a heavy metalsample having a low concentration, there is a possibility that thedetection sensitivity and limit are lowered because the sample fails tosufficiently react with the organic chelating agent on the detectionunit, and thus the color development does not occur. However, accordingto the present invention, since the centrifugal force acts on theopposite side of the capillary force, the centrifugal force is appliedto control the solution development speed by the capillary force so thatthe color development reaction can be sufficiently performed on thedetection unit to improve the detection limitations.

Further, according to the device for qualitative analysis andquantitative analysis (1, 1′, 1″, 1′″) and the method of analyzing thesample (2) using the same according to the embodiment of the presentinvention, it is economical and quick in the qualitative/quantitativeanalysis of multiple heavy metals. It is more economical thanconventional expensive spectroscopy or mass spectrometry based heavymetal detector and can shorten analysis time. Thus, it can be appliedquickly and conveniently in the field where the qualitative/quantitativeanalysis of heavy metals is required.

The technical constitution of the present invention as described abovewill be understood by those skilled in the art that various changes inform and details may be made therein without departing from the spiritand scope of the invention. It is therefore to be understood that theabove-described embodiments are illustrative in all aspects and notrestrictive. In addition, the scope of the present invention isindicated by the appended claims rather than the detailed description ofthe invention. Also, all changes or modifications derived from themeaning and scope of the claims and their equivalents should beconstrued as being included within the scope of the present invention.

EXPLANATION OF REFERENCE NUMBERS

1, 1′, 1″, 1′″: Device for qualitative analysis and quantitativeanalysis

2: Method of analyzing a sample

3: System for qualitative analysis and quantitative analysis

10: Rotatable platform

20, 20′, 20″, 20′″: Microfluidic structure

100: Sample injection unit

110: Microfluidic channel

120, 120′, 120″: Detection unit

130: Ruler

What is claimed is:
 1. A device for qualitative analysis andquantitative analysis comprising a rotatable platform and a plurality ofmicrofluidic structures disposed radially and symmetrically on therotatable platform, wherein each of the plurality of the microfluidicstructures comprises: a sample injection unit configured to receive aninjection of a respective fluid sample containing heavy metals, anentirety of the sample injection unit being located in a top layer ofthe rotatable platform, the sample injection unit including a spaceconfigured to receive an entirety of the respective fluid sample storedtherein and an opening configured to receive the injection of therespective fluid sample; a microfluidic siphon channel which is apassage providing fluid communication between the sample injection unitand one end of a detection unit; the detection unit comprising aplurality of detection members each being coated with a respectivedifferent reagent, each reagent containing a different organic material,each organic material containing organic ligands configured to produce acolor development reaction with the heavy metals of the fluid sample;and a ruler configured to measure a color developed distance of thecolor development reaction, the ruler being positioned alongside thedetection unit, wherein each of the plurality of the microfluidicstructures is configured to receive a different kind of the respectivefluid samples than other ones of the plurality of the microfluidicstructures, wherein the device is configured to move the respectivefluid samples from the respective sample injection unit to therespective microfluidic channel and then to the respective detectionunit when the rotatable platform is rotated, wherein the device isconfigured to provide the qualitative analysis of the fluid samplesthrough the respective color development reaction of the heavy metals inthe respective detection unit and the device is configured to providethe quantitative analysis of the fluid samples through measurement ofthe respective color developed distances, wherein each detection unitcomprises a respective reservoir area which connects one end of each ofthe plurality of the detection members with the respective microfluidicchannel, each of the detection members of each detection unit comprisesa respective plurality of three or more sections coated with therespective different reagent, each section being coated with therespective organic material having different respective concentrationsof the organic ligands, an entirety of each section being coated withthe respective organic material having the different respectiveconcentrations of the organic ligands, each of the detection memberscomprising a respective development area coated with the respectiveorganic material configured to produce the color development reactionwith the heavy metals of the respective fluid sample so that therespective fluid sample is developed, wherein the development area ofeach detection member is located closer to a center of the rotatableplatform than the reservoir area of the respective detection unit, suchthat each detection member is configured to move the respective fluidsample from the respective reservoir to the respective development areain a direction from a periphery of the rotatable platform towards thecenter of the rotatable platform via a capillary force, and theplurality of sections of each detection member being disposed adjacentto one another along a longitudinal direction of the detection member,the plurality of sections of each detection member being configured toreceive a respective portion of a respective one of the fluid samplesflowing successively through the sections from a first section closestto the respective reservoir area towards a last section farthest fromthe respective reservoir area, the first section of each developmentarea being coated with a highest concentration of the organic ligand,the plurality of sections of each detection member being continuouslyarranged so that boundaries thereof are in contact with each other alongthe longitudinal direction of the detection member.
 2. The deviceaccording to claim 1, wherein the concentration of the organic ligandsof the organic material coated in the section of each detection memberlocated i-th from the respective reservoir area is lower than theconcentration of the organic ligands of the organic material coated inthe section located i-1-th from the respective reservoir area, wherein iis a natural number from 1 to n.
 3. The device according to claim 1,further comprising a respective air circulation channel connecting eachsample injection unit and another end of each respective detection unit,wherein each air circulation channel is configured to increase a rate ofevaporation of the fluid sample in the respective detection unit and isconfigured to prevent a moisture condensation phenomenon in therespective detection unit.
 4. The device according to claim 1, whereinthe device is configured to move the respective fluid samples by: afirst rotation of the rotatable platform and then stopping the firstrotation so that the fluid sample injected into each respective sampleinjection unit is moved to the respective microfluidic siphon channel; asecond rotation of the rotatable platform so that the fluid sample movedto each respective microfluidic channel is moved to the respectivereservoir area; and stopping rotation of the rotatable platform so thatthe fluid sample moved to each respective reservoir area is developed inthe detection unit.
 5. The device according to claim 4, wherein eachmicrofluidic siphon channel includes a portion of a “U” shaped tube thatis configured to receive the respective fluid sample after the firstrotation and before the second rotation of the rotatable platform. 6.The device according to claim 4, wherein the first rotation of therotatable platform is performed at 2000 to less than 4000 RPM for 5 to20 seconds and the second rotation of the rotatable platform isperformed at 4000 to 6000 RPM for 3 to 10 seconds.
 7. The deviceaccording to claim 1, wherein the heavy metals included in each of thefluid samples comprise Fe²⁺, Zn²⁺, Hg²⁺, Cr⁶⁺, Ni²⁺, or Cu²⁺.
 8. Thedevice according to claim 7, wherein the organic material that coats thedetection units comprises any one selected from the group consisting ofdimethylglyoxime, bathophenanthroline, dithiooxamide, dithizone,diphenylcarbazide and 1-(2-pyridylazo)-2-naphthol.
 9. The deviceaccording to claim 1, wherein, within each detection member, the lastsection has a lowest one of the respective concentrations.
 10. A methodof analyzing the fluid samples by using the device according to claim 1,the method comprising: injecting each fluid sample into the respectivesample injection unit; rotating the rotatable platform; and performingat least one of the qualitative analysis and the quantitative analysisof the fluid sample developed in each respective detection unit.
 11. Themethod according to claim 10, wherein the injecting of each fluid sampleinto the respective sample injection unit comprises: injecting a firstamount of each fluid sample into the respective one of the microfluidicstructures; or injecting a second amount of each fluid sample into therespective one of the microfluidic structures, the first amount of eachfluid sample having a different concentration than the second amount ofeach fluid sample.
 12. The method according to claim 10, wherein theperforming of the at least one of the qualitative analysis and thequantitative analysis of each fluid sample comprises: performing the atleast one of the qualitative analysis through the color developmentreaction of each sample developed in the respective detection unit andthe quantitative analysis through the measurement of the respectivecolor developed distance.
 13. A method of analyzing the fluid samples byusing the device according to claim 1, the method comprising: injectingeach fluid sample into the respective sample injection unit; rotatingthe rotatable platform; and performing at least one of the qualitativeanalysis and the quantitative analysis of the fluid sample developed ineach respective detection unit, wherein the rotating of the rotatableplatform comprises: rotating the rotatable platform firstly and thenstopping the rotating so that the fluid sample injected into eachrespective sample injection unit is moved to the respective microfluidicchannel; rotating the rotatable platform secondarily so that the fluidsample moved to each microfluidic channel is moved to the respectivereservoir area; and stopping the rotation of the rotatable platform sothat the sample moved to each reservoir area is developed in therespective detection unit.